Localization of horseradish peroxidase-alpha-bungarotoxin binding in crustacean axonal membrane vesicles and intact axons.

Abstract

A conjugate of .alpha.-bungarotoxin with horseradish peroxidase was used to visualize .alpha.-bungarotoxin binding sites at the fine structural level in isolated axonal membrane vesicles from lobster walking leg nerve. These plasma membrane vesicles were previously shown to exhibit saturable binding of [3H]nicotine and [3H]acetylcholine. Binding of the toxin was identified in the axon plasma membrane and could be blocked by pretreatment with excess free .alpha.-bungarotoxin or d-tubocurarine. Binding sites for .alpha.-bungarotoxin were identified by the same technique in sections of intact nerve fibers from both lobster and spider crab [Libinia emarginata] and were found to be localized primarily in the axolemma rather than in the Schwann cell membrane.